Packaging of respiring biological materials

ABSTRACT

Packaging of respiring biological materials, particularly bananas and other fruits, in sealed containers. The containers preferably include a gas-permeable membrane comprising (1) a microporous film, and (2) a polymeric coating on the microporous film. Using appropriate containers and appropriate controlled atmospheres around the container, the respiring materials can be stored and/or ripened under controlled conditions. Bananas can be ripened while they are being transported, or in conventional ripening rooms without opening the containers in which they have been transported. The ripe bananas are less dehydrated and remain in a satisfactory ripened state for longer periods of time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of my commonly assigned applicationSer. No. 09/989,682, filed Nov. 20, 2001 now U.S. Pat. No. 7,601,374,which is a continuation-in-part of my commonly assigned application Ser.No. 09/858,190 now issued, filed May 15, 2001, which claims priorityunder 37 CFR 1.78 (a)(5) from provisional Application Ser. No.60/325,762. Application Ser. No. 60/325,762 has an effective filing dateof May 26, 2000, and resulted from the conversion to a provisionalapplication of application Ser. No. 09/580,379, filed May 26, 2000. Thisapplication is also related to International Application No. PCT/US01/40732, filed May 15, 2001. The disclosure of each of theabove-identified applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to the packaging of respiring biologicalmaterials.

Respiring biological materials, e.g. fruits and vegetables, consumeoxygen (O₂) and produce carbon dioxide (CO₂) at rates which depend uponthe stage of their development, the atmosphere surrounding them and thetemperature. In modified atmosphere packaging (MAP), the objective is toproduce a desired atmosphere around respiring materials by placing themin a sealed container whose permeability to O₂ and CO₂ is correlatedwith (i) the partial pressures of O₂ and CO₂ in the air outside thepackage, and (ii) the temperature, to produce a desired atmospherewithin the container. In many cases, the container includes anatmosphere control member having a high permeability to O₂ and CO₂. Incontrolled atmosphere packaging (CAP), the objective is to produce adesired atmosphere around respiring materials by displacing some or allof the air within a container by one or more gases, e.g. nitrogen, O₂,CO₂ and ethylene, in desired proportions. Reference may be made, forexample, to U.S. Pat. No. 3,360,380 (Bedrosian), U.S. Pat. No. 3,450,542(Badran), U.S. Pat. No. 3,450,544 (Badran et al.), U.S. Pat. No.3,798,333 (Cummin et al), U.S. Pat. No. 3,924,010 (Erb), U.S. Pat. No.4,003,728 (Rath), U.S. Pat. No. 4,734,324 (Hill), U.S. Pat. No.4,779,524 (Wade), U.S. Pat. No. 4,830,863 (Jones), U.S. Pat. No.4,842,875 (Anderson), U.S. Pat. No. 4,879,078 (Antoon), U.S. Pat. No.4,910,032 (Antoon), U.S. Pat. No. 4,923,703 (Antoon), U.S. Pat. No.4,987,745 (Harris), U.S. Pat. No. 5,041,290 (Wallace et al.) U.S. Pat.No. 5,045,331 (Antoon), U.S. Pat. No. 5,063,753 (Woodruff), U.S. Pat.No. 5,160,768 (Antoon), U.S. Pat. No. 5,254,354 (Stewart), U.S. Pat. No.5,333,394 (Herdeman), U.S. Pat. No. 5,433,335 (Raudalus et al.), U.S.Pat. No. 5,460,841 (Herdeman), U.S. Pat. No. 5,556,658 (Raudalus etal.), U.S. Pat. No. 5,658,607 (Herdeman) and U.S. Pat. No. 6,013,293 (DeMoor), copending commonly assigned U.S. patent application Ser. No.08/759,602 (Clarke et al.) and Ser. No. 09/121,082 (Clarke et al.),International Publication Nos. WO 94/12040 (Fresh Western), WO 96/38495(Landec) and WO 00/04787 (Landec), and European Patent Applications Nos.0,351,115 and 0,351,116 (Courtaulds). The disclosure of each of thesepatents, applications and publications is incorporated herein byreference.

The preferred packaging atmosphere for a respiring material oftendepends on the age of the material and the changes (if any) in thematerial which are desired. For example, the preferred O₂ content duringstorage of unripe fruits is substantially lower than the preferred O₂content during subsequent ripening at a higher temperature. This factcauses problems for both MAP and CAP. For example, in MAP, although theO₂ permeability of the container generally increases with temperature(especially if it contains an atmosphere control member comprising acrystalline polymer having an appropriate melting point, as disclosed inU.S. patent applications Ser. Nos. 08/759,602 and 09/121,082 andInternational Publication Nos. WO 96/38459 and WO 00/04787), theincrease is often insufficient to avoid the need for significantcompromise between the preferred atmospheres at different stages. InCAP, it is theoretically possible to monitor the packaging atmosphereand to change it as often as is necessary to maintain the preferredlevel of O₂ (and other gases). But this is difficult and expensive, andoften impractical.

Many fruits are picked when they are unripe; transported and storedunder conditions which prevent or retard ripening; and ripen shortlybefore sale. Many fruits ripen more rapidly when exposed to ethylene,and some (e.g. bananas, tomatoes, avocados, Bartlett pears, kiwis,melons, peppers and mangos) are ripened commercially by exposure toethylene in ripening rooms. When the fruits have been placed in a sealedbag or other container for transport or storage, the container is openedto expose the fruits to the ethylene. Another problem associated withthe use of ripening rooms is that the fruits can ripen too rapidly,especially when the fruits ripen through a climacteric and thereforeundergo a very large increase in respiration rate and generate heat inthe ripening room.

The transport, storage and ripening of bananas present particularlyserious problems because

(i) bananas are grown in locations far distant from the locations atwhich they are consumed;

(ii) they are damaged by storage at temperatures below about 14° C.(57-58° F.), with the extent of the damage depending upon the time spentbelow that temperature and how far the temperature is below 14° C.;

(iii) they ripen through a climacteric, and this results in a very largeincrease in respiration rate and the generation of heat;

(iv) they generate ethylene as they ripen, and they ripen at a ratewhich increases with the concentration of ethylene around them—as aresult, a single prematurely ripe banana can trigger premature ripeningof many others; and

(iv) once they have ripened, and have been exposed to air, they rapidlybecome over-ripe.

These problems have not yet been solved. The conventional procedure isto harvest the bananas when they are hard, green and unripe; totransport the green bananas, at 14-18° C. to the location where theywill be consumed; to ripen the green bananas by exposing them toethylene in a ripening room at that location; and to place the ripenedbananas on sale. The time at which the bananas are harvested depends onthe days needed to transport them to the point-of-sale. Thus bananas aretypically harvested at week 11 (i.e. 11 weeks after the flower emergesfrom the plant) or week 12. The green bananas are shipped in bags madeof polyethylene about 0.04 to 0.06 mm (1.5-2.5 mil) thick, with each bagcontaining about 18 kg (40 lb) of bananas and being supported by acardboard box. In some cases, after the bananas have been placed in thebag, most of the air is exhausted from the bag, and the bag is thensealed; this is the procedure generally described in U.S. Pat. No.3,450,542 (Badran). In other cases, the bag contains vent holes.

This conventional procedure suffers from a number of problems, forexample:

-   1. The need to harvest the bananas a good while before they are    fully grown. It would be desirable to harvest the bananas at a later    time, when they are larger. However, the later the bananas are    picked, the more likely it is that their climacteric will be    triggered by small concentrations of ethylene. Experience has shown    that if bananas are harvested later than the presently established    timetables, this results in prematurely ripe bananas when the    bananas are shipped in vented bags, and in so-called “green-ripe”    bananas when the bananas are shipped in sealed bags. Green-ripe    bananas soften, but remain green, and have an unpleasant flavor.-   2. In order to ripen green bananas in a ripening room, it is    necessary to open each of the shipping bags if the bags have been    sealed during shipping.-   3. Bananas ripen very rapidly, which heats the bananas excessively    and/or increases the demand on the refrigeration equipment used to    cool the ripening room.-   4. The bananas, once ripened, must be sold within a few days, or    scrapped.

SUMMARY OF THE INVENTION

A first area of the present invention is based on my realization thatfor bananas and other fruits which ripen when exposed to ethylene, oneor more of the problems noted above can be mitigated or overcome byripening fruits within a sealed container which provides a pathway forO₂, CO₂ and ethylene to enter or leave the container. The fruits can beripened by exposing them to ethylene which (i) enters the container froman ethylene-containing atmosphere adjacent to the sealed containerand/or (ii) is generated within the sealed container.

A second area of the present invention is concerned with situations inwhich the preferred packaging atmosphere has a zero or relatively lowcontent of a particular gas during one stage and a relatively highcontent of that gas during another stage, in particular a relatively lowO₂ content during one stage and a relatively high O₂ content duringanother stage. I have realized that in such situations, valuable resultscan be obtained by combining the techniques of MAP and CAP. For example,a container having a high O₂ permeability can be placed either (i) inair when a packaging atmosphere of high O₂ content is desired, or (ii)in a controlled atmosphere having a selected reduced O₂ content when apackaging atmosphere of low O₂ content is desired.

Some aspects of the present invention make use of both the first andsecond areas of the invention.

As noted above, some fruits generate ethylene as they ripen. Suchethylene is referred to herein as endogenous ethylene. The term“exogenous ethylene” is used herein to mean ethylene which is notderived from the fruits which are being ripened. Some other materials,for example acetylene, will also assist ripening of fruits which areripened by exposure to ethylene. Reference may made for example to Burget al, Molecular Requirements for the Biological Activity of Ethylene,Plant Physiology (Lancaster) (1967) 42: 144-155. The term “ethylenicripening agent” is used herein to mean ethylene or another substancewhich also assists ripening of fruits which are ripened by exposure toethylene. The abbreviation ERA is used herein for the term “ethylenicripening agent”. The term “exogenous ERA” is used herein to meanethylenic ripening agent which is not derived from the fruits which arebeing ripened.

The first area of the invention includes the following aspects.

-   I. A method of ripening fruits, the method comprising

(A) providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, (i) unripe fruits which ripen        when exposed to ERA and (ii) a packaging atmosphere around the        unripe fruits; the sealed container providing a pathway for O₂,        CO₂ and ERA to enter or leave the packaging atmosphere; and

(B) exposing the exterior of the sealed package to an atmosphere whichcontains exogenous ERA.

-   II. A method of ripening fruits, the method comprising

(A) providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, (i) unripe fruits which ripen        when exposed to exogenous ERA, (ii) a packaging atmosphere        around the unripe fruits and (iii) a source of exogenous ERA;        the sealed container providing a pathway for O₂, CO₂ and ERA to        enter or leave the packaging atmosphere; and

(B) exposing the unripe fruits in the sealed package to exogenous ERAfrom the source of exogenous ERA in the sealed container.

-   III. A sealed package which comprises    -   (a) a sealed container, and    -   (b) within the sealed container, (i) fruits, for example fruits        which have ripened through a climacteric, (ii) a packaging        atmosphere around the fruits, and (iii) exogenous ERA and/or a        residue of exogenous ERA, the exogenous ERA and/or residue of        exogenous ERA optionally being a gas which is part of the        packaging atmosphere;    -   the sealed container providing a pathway for O₂, CO₂ and ERA to        enter or leave the packaging atmosphere.-   IV. A package which comprises    -   (a) a container, the container being a sealed container or an        open container obtained by opening a sealed container, and    -   (b) within the container, (i) fruits, and (ii) a packaging        atmosphere around the fruits; the container, if it is sealed,        providing a pathway for O₂, CO₂ and ERA to enter or leave the        packaging atmosphere, and if it is open, having provided a        pathway for O₂, CO₂ and ERA to enter or leave the packaging        atmosphere when it was sealed;    -   the container having one or both of the following        characteristics        -   (i) the fruits therein have been ripened at least in part by            exposure to exogenous ERA, and        -   (ii) it contains the residue of a source of exogenous ERA.            For example, the container can be a sealed or open container            in which the fruits have ripened through a climacteric as a            result of exposure to ethylene in a ripening room, or as a            result of exposure to exogenous ERA generated within the            container while it was sealed.-   V. A container, for example a shipping or trucking container, which    may be a closed container or an open container, which contains a    plurality of sealed packages, each of the packages comprising

(a) a sealed container, and

(b) within the sealed container, (i) fruits, for example fruits whichhave ripened through a climacteric, or unripe fruits which ripen througha climacteric, and (ii) a packaging atmosphere around the fruits;

the sealed container providing a pathway for O₂, CO₂ and ERA to enter orleave the packaging atmosphere;

the container containing the plurality of sealed packages having atleast one of the following features

-   -   (i) the packaging atmosphere in each of the sealed packages        contains exogenous ERA and/or a residue of exogenous ERA;    -   (ii) at least some, and preferably each, of the sealed packages        contains and exogenous ERA and/or a residue of exogenous ERA,        the exogenous ERA and/or residue of exogenous ERA optionally        being a gas which is part of the packaging atmosphere, or    -   (iii) the shipping or trucking or other container contains not        only the sealed packages containing the fruits but also, not        within any of the sealed packages, exogenous ERA and/or a        residue of a source of exogenous ERA, the exogenous ERA and/or        residue of a source of exogenous ERA optionally being a gas        which is part of the atmosphere which contacts the exterior of        the sealed packages.

The second area of the invention includes the following aspects.

-   VI. A method of storing and/or ripening a respiring biological    material, the method comprising

(A) providing a sealed package comprising

-   -   (a) a sealed container, and    -   (b) within the sealed container, the respiring biological        material;    -   the sealed container providing a pathway for O₂ and CO₂ to enter        or leave the packaging atmosphere;

(B) exposing the exterior of the sealed package to a first atmospherecontaining O₂;

(C) after step (B), exposing the exterior of the sealed package to asecond atmosphere containing O₂;

the first and second atmospheres differing by at least 1% in theircontent of at least one gas which will pass through the container.Preferably there is a difference between the O₂ contents of the firstand second atmospheres of at least 3%.

The O₂ contents of the packaging atmospheres in steps (B) and (C) willbe lower than the O₂ contents of the atmospheres surrounding thepackage, and any difference between them will be less than anydifference between the O₂ contents of the first and second atmospheres.Preferably, one of the first and second atmospheres is air.

This aspect of the invention is useful for the treatment of anyrespiring biological material, including but not limited to, fruits(e.g. fruits which have ripened through a climacteric, or unripe fruitswhich ripen through a climacteric) and vegetables.

In one embodiment of this aspect of the invention,

(a) in step (B), the first atmosphere is a controlled atmosphere havinga reduced O₂ content, for example (i) less than 18% O₂, preferably lessthan 12% O₂, particularly less than 9% O₂, but (ii) more than 2% O₂,preferably more than 4% O₂, particularly more than 5% O₂, and thepermeability of the container is such that the O₂ content of thepackaging atmosphere is high enough to maintain respiration of thebiological material (for example, in the case of unripe fruits, an O₂content which is high enough to maintain respiration of the fruits, butlow enough that the unripe fruits ripen slowly or not at all), and

(c) in step (C), the second atmosphere contains at least 3% more oxygenthan the first atmosphere.

In this embodiment, when the package contains unripe fruits, the secondatmosphere optionally contains exogenous ERA, and is preferably air or amixture of air and exogenous ERA. This results in an increase in the O₂content of the packaging atmosphere, thus assisting the unripe fruits toripen.

In another embodiment of this aspect of the invention,

(a) the sealed packages contain fruits which initially are unripe,

(b) in step (B), the first atmosphere is air, and the permeability ofthe container is such that the O₂ content of the packaging atmosphere ishigh enough to maintain respiration of fruits, but low enough that theunripe fruits ripen slowly or not at all, and

(c) in step (C), the second atmosphere contains at least 3% more oxygenthan the first atmosphere, and preferably has an O₂ content of at least24%, particularly at least 28% oxygen, thus increasing the O₂ content ofthe packaging atmosphere and assisting the unripe fruits to ripen.

In step (C), the fruits can if desired be exposed to exogenous ERA, forexample by including exogenous ERA in the second atmosphere, and/or byincluding a source of exogenous ERA within the sealed package, and/or,when there are a plurality of packages in a large container, e.g. ashipping or trucking container, by including a source of ethylenicripening agent within the large container, but outside the sealedpackages. This embodiment of the invention can be used to transport andripen bananas in a sealed container, for example a conventionalpolyethylene bag, whose oxygen permeability is too low to permitsatisfactory ripening in the atmospheres used in conventional ripeningrooms.

In these two embodiments, it is preferred that, during at least oneperiod of step (B), the O₂ content of the packaging atmosphere reaches avalue, which may be an equilibrium value, which is (i) more than 1%,preferably more than 2%, and (ii) less than 7%, preferably less than 5%,particularly less than 3.5%.

In another embodiment of this aspect of the invention, the first andsecond atmospheres differ in their content of some gas other than oxygenwhich will pass through the sealed container, for example CO₂ or anothergas having a desired effect on the respiring biological material, e.g.an insecticide, a fungicide or a mold-inhibiting compound. One of theatmospheres can contains 0% of the gas other than oxygen. In thisembodiment, the O₂ content of the first and second atmospheres can bethe same or different. For example, this embodiment of the inventioncode be used to store the respiring material in the sealed package underpreferred conditions during one of steps (B) and (C), and in the otherstep to use a controlled atmosphere to change the packaging atmosphere,for a relatively short time, to an atmosphere containing a desiredamount of the gas other than oxygen, for example to contact therespiring material with an atmosphere containing a relatively highpercentage of CO₂, e.g. 15-30%, for a relatively limited period of time,e.g. for 5-48 or 15-30 hours. Such a method would be useful, forexample, for the treatment of broccoli to control aphids.

The invention is particularly useful for the storage and/or ripening ofbananas. Some embodiments of the invention make it possible to maintainbananas, before and/or after their climacteric, in a packagingatmosphere which enables storage and/or ripening of green bananas in acontrolled fashion. Other embodiments of the invention make it possibleto ripen bananas in a sealed container, for example in a conventionalripening room or in a closed container in which the bananas are beingtransported; and/or to harvest bananas at a later time than is nowpossible; and/or to store bananas, after their climacteric, within adesired range of color stages (e.g. within the range most attractive forretail sale) for a longer period than is possible under conventionalpractice.

Some embodiments of the invention which are particularly suitable forthe ripening and/or storage of bananas have been described above. Otheraspects of the invention which are particularly suitable for theripening and/or storage of bananas include the following.

-   VII. A container which is suitable for packaging bananas and which    can be sealed around a quantity of bananas, said quantity being at    least 4 kg, preferably at least 15 kg, especially 16 to 22 kg, and    which, when sealed around the bananas, has an O₂ permeability at    13° C. per kg of bananas in the container (abbreviated herein to    OP13/kg) of at least 700, preferably at least 1000, particularly at    least 1500, ml/atm.24 hrs. In some embodiments, the container has an    R ratio at 13° C. of at least 1.3, particularly at least 2,    especially at least 3. In some embodiments, the container has an    ethylene permeability at 13° C. per kg of bananas in the container    (abbreviated herein to EtP/13 kg) which is at least 2 times,    preferably at least 3 times, particularly at least 4 times, the    OP13/kg of the container.

It is to be understood that this aspect of the invention includescontainers which are as defined above but which are used for thepackaging of fruits other than bananas. It is also to be understood thatthe containers defined above can be used to ripen fruits by exposingthem to any exogenous ERA. When ripening fruits by exposing them to anexogenous ERA other than ethylene, the containers preferably have apermeability at 13° C. to that ERA per kg of bananas which is at leasttwo times, preferably at least 3 times, particularly at least 4 times,the OP13/kg of the container.

-   VIII. A package which comprises

(a) a sealed container, and

(b) within the sealed container, bananas and a packaging atmospherearound the bananas;

the sealed container having an OP13/kg of at least 700, preferably atleast 1000, particularly at least 1500, ml/atm.24 hrs. In someembodiments, the sealed container has an R ratio at 13° C. of 1.3,particularly at least 2, especially at least 3.

-   IX. A method of ripening green bananas which comprises

(A) providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, green bananas and a packaging        atmosphere around the green bananas;    -   the sealed container having an OP13/kg of at least 700,        preferably at least 1000, particularly at least 1500, ml/atm.24        hrs, and preferably having an R ratio at 13° C. of at least 1.3,        particularly at least 2, especially at least 3, and preferably        having an EtP/13 kg which is at least 3 times, preferably at        least 4 times, the OP13/kg of the container; and

(B) exposing the exterior of the sealed package to an atmospherecontaining exogenous ERA.

-   X. A method of ripening green bananas which comprises

(A) placing, in a sealable container,

-   -   (a) the green bananas, and    -   (b) a source of exogenous ERA;

(B) sealing the container around the green bananas and the source ofexogenous ERA, thus providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, the green bananas, the source        of exogenous ERA, and a packaging atmosphere around the green        bananas;    -   the sealed container having an OP13/kg of at least 700,        preferably at least 1000, particularly at least 1500, ml/atm.24        hrs, and preferably having an R ratio at 13° C. of at least 1.3,        particularly at least 2, especially at least 3, and preferably        having an EtP/13 kg which is at least 3 times, preferably at        least 4 times, the OP13/kg of the container; and

(C) exposing the bananas in the sealed package to exogenous ERA from thesource of exogenous ERA in the sealed container.

-   XI. A method of storing green bananas which comprises

(A) placing the green bananas in a container which comprises anatmosphere control member which preferably comprises

-   -   (1) a microporous film, and    -   (2) a polymeric coating, preferably a crystalline polymeric        coating, on the microporous film;

(B) sealing the container, thus providing a sealed package whichcomprises

-   -   (a) a sealed container, and    -   (a) within the sealed container, the green bananas, and a        packaging atmosphere around the green bananas; and

(C) maintaining the sealed bag at the temperature of 13-18° C.

-   XII. A package which is stored in air and which comprises

(a) a sealed container, and

(b) within the sealed container, 1 to 6 kg, e.g. 1 to 2.5 kg (2 to 15lb, e.g. 2 to 5 lb) of bananas which have passed their climacteric andwhich are at a color stage less than 5, and a packaging atmospherearound the bananas; the sealed container providing a pathway for O₂ andCO₂ to enter or leave the packaging atmosphere;

the packaging atmosphere preferably containing at least 0.8%, preferably1.5 to 6%, especially 1.5 to 3%, of O₂, and less than 15%, preferablyless than 7%, of CO₂, and the total quantity of O₂ and CO₂ preferablybeing less than 16%, particularly less than 10%.

-   XIII. A package which comprises

(a) a sealed container, and

(b) within the sealed container, bananas and a packaging atmospherearound the bananas;

the sealed container including at least one permeable control memberwhich provides a pathway for O₂, CO₂ and ERA to enter or leave thepackaging atmosphere and which comprises a gas-permeable membranecomprising

(a) a microporous polymeric film, and

(b) a crystalline polymeric coating on the microporous film.

-   XIV. A method of ripening green bananas which comprises

(A) providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, green bananas and a packaging        atmosphere around the green bananas;    -   the sealed container including at least one permeable control        member which provides a pathway for O₂, CO₂ and ERA to enter or        leave the packaging atmosphere; and

(B) exposing the exterior of the sealed package to an atmospherecontaining exogenous ERA.

-   XV. A method of ripening green bananas which comprises

(A) placing, in a sealable container,

-   -   (a) the green bananas, and    -   (b) a source of exogenous ERA;

(B) sealing the container around the green bananas and the source ofexogenous ERA, thus providing a sealed package which comprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, the green bananas, the source        of exogenous ERA, and a packaging atmosphere around the green        bananas;    -   the sealed container providing a pathway for O₂, CO₂ and ERA to        enter or leave the packaging atmosphere; and

(C) exposing the bananas in the sealed package to exogenous ERA from thesource of exogenous ERA in the sealed container.

-   XVI. A method of storing green bananas which comprises

(A) placing the green bananas in a sealable container;

(B) sealing the container, thus providing a sealed package whichcomprises

-   -   (a) a sealed container, and    -   (b) within the sealed container, the green bananas, and a        packaging atmosphere around the green bananas;    -   the sealed container providing a pathway for O₂ and CO₂ to enter        or leave the packaging atmosphere and

(C) maintaining the sealed bag at the temperature of 13-18° C.

-   XVII. A method of storing green bananas, the method comprising

(A) providing a sealed package comprising (a) a sealed container, and(b) within the sealed container, the green bananas and a packagingatmosphere around the green bananas; the sealed container providing apathway for O₂ and CO₂ to enter or leave the packaging atmosphere; and

(B) storing the sealed package in a controlled atmosphere which contains(i) less than 18% O₂, preferably less than 12% O₂, particularly lessthan 9% O₂, and (ii) more than 2% O₂, preferably more than 4% O₂,particularly more than 5% O₂, the sealed package having an O₂permeability such that, during at least one period of step (B), the O₂content of the packaging atmosphere reaches a value, which may be anequilibrium value, which is (i) more than 1%, preferably more than 2%,and (ii) less than 7%, preferably less than 5%, particularly less than3.5%.

It is possible for the bananas to ripen under the storage conditionswithout the use of exogenous ERA. However, the method preferably furthercomprises

(C) during or after step (B), exposing the fruits to exogenous ERA,preferably by exposing the exterior of the sealed package to a secondcontrolled atmosphere which contains exogenous ERA, especially a mixtureof air and exogenous ethylene, thereby ripening the bananas.

-   XVIII. A method of storing and ripening green bananas, the method    comprising

(A) providing a sealed package comprising (a) a sealed container, and(b) within the sealed container, the green bananas, a packagingatmosphere around the green bananas, and a latent source of exogenousERA;

-   -   the sealed container providing a pathway for O₂ and CO₂ to enter        or leave the packaging atmosphere; and

(B) storing the sealed package (a) under conditions such that ERA is notreleased from the latent source and (b) in a controlled atmosphere whichcontains (i) less than 18% O₂, preferably less than 12% O₂, particularlyless than 9% O₂, and (ii) more than 2% O₂, preferably more than 4% O₂,particularly more than 5% O₂, the sealed package having an O₂permeability such that, during at least one period of step (B), the O₂content of the packaging atmosphere reaches a value which is (i) morethan 1%, preferably more than 2%, and (ii) less than 7%, preferably lessthan 5%, particularly less than 3.5%; and

(C) during or after step (B), activating the latent source of exogenousERA, thereby releasing exogenous ERA which ripens the bananas.

-   XIX. The use, in packaging bananas, of a container including at    least one permeable control member which provides a pathway for O₂    and CO₂, and which comprises a gas-permeable membrane comprising (1)    a microporous film, and (2) a crystalline polymeric coating on the    microporous film.

DETAILED DESCRIPTION OF THE INVENTION

In the Summary of the Invention above and in the Detailed Description ofthe Invention, the Examples, and the Claims below, reference is made toparticular features (including method steps) of the invention. It is tobe understood that the disclosure of the invention in this specificationincludes all appropriate combinations of such particular features. Forexample, where a particular feature is disclosed in the context of aparticular aspect or embodiment of the invention, or a particular claim,that feature can also be used, to the extent appropriate, in combinationwith and/or in the context of other particular aspects and embodimentsof the invention, and in the invention generally.

In describing and claiming the invention below, the followingabbreviations, definitions, and methods of measurement (in addition tothose already given) are used.

OTR is O₂ permeability. COTR is CO₂ permeability. EtTR is ethylenetransmission rate. OTR, COTR and EtTR values are given in ml/m².atm.24hrs; in some cases, the equivalent in cc/100 inch².atm.24 hrs is givenin parentheses. OTR and COTR values referred to herein can be measuredusing a permeability cell (supplied by Millipore) in which a mixture ofO₂, CO₂ and helium is applied to the sample, using a pressure of 0.7kg/cm² (10 psi) except where otherwise noted, and the gases passingthrough the sample were analyzed for O₂ and CO₂ by a gas chromatograph.The cell could be placed in a water bath to control the temperature. Theabbreviation P₁₀ is used to mean the ratio of the oxygen permeability ata first temperature T₁° C. to the oxygen permeability at a secondtemperature T₂, where T₂ is (T₁−10)° C. T₁ being 10° C. and T₂ being 0°C. unless otherwise noted. The abbreviation R or R ratio is used to meanthe ratio of CO₂ permeability to O₂ permeability, both permeabilitiesbeing measured at 20° C. unless otherwise noted. Pore sizes given inthis specification are measured by mercury porosimetry or an equivalentprocedure. Parts and percentages are by weight, except for percentagesof gases, which are by volume; temperatures are in degrees Centigrade,and molecular weights are weight average molecular weights expressed inDaltons. For crystalline polymers, the abbreviation T_(o) is used tomean the onset of melting, the abbreviation T_(p) is used to mean thecrystalline melting point, and the abbreviation ΔH is used to mean theheat of fusion. T_(o), T_(p) and ΔH are measured by means of adifferential scanning calorimeter (DSC) at a rate of 10° C./minute andon the second heating cycle. T_(o) and T_(p) are measured in theconventional way well known to those skilled in the art. Thus T_(p) isthe temperature at the peak of the DSC curve, and T_(o) is thetemperature at the intersection of the baseline of the DSC peak and theonset line, the onset line being defined as the tangent to the steepestpart of the DSC curve below T_(p).

The term “comprises” (and grammatical variations thereof) in relation tomethods, materials, things etc. (for example packages, containers, andgas-permeable membranes) are used herein to mean that the methods,materials, things etc. can optionally include, in addition to the steps,features, components, etc., explicitly specified after the term“comprises” (and grammatical variations thereof), other steps, features,ingredients, etc. Where reference is made herein to a method comprisingtwo or more steps, the steps can be carried out in any order, orsimultaneously, except where the context excludes that possibility. Theterm “controlled atmosphere” is used herein to mean an atmosphereproduced by adding further gases to an existing atmosphere (includingthe addition of additional quantities of a gas already present in theexisting atmosphere), the further gases being added directly to theatmosphere (i.e. not passing through a permeable body before reachingthe atmosphere). The term “closed container” is used herein to mean alarge container, for example a conventional shipping or truckingcontainer which can be loaded onto a ship or a truck, and which issealed sufficiently to permit a controlled atmosphere to be maintainedtherein by conventional means well known to those skilled in the art.The term “shipping or trucking container” is used herein to mean acontainer which has a volume of at least 8 m³ and which can be loadedonto a ship or a truck. Such containers are well known to those skilledin the art of storing and transporting fruits, vegetables and otherrespiring materials, and are available in a range of standard sizes. Theterm “source of exogenous ERA” is used herein to mean a material, objector system which, either immediately or when activated, generates ERA.The term “latent source of exogenous ERA” is used herein to mean amaterial, object or system which is generating little or no ERA, butwhich can be activated so that it generates substantial quantities ofexogenous ERA. The term “residue of a source of exogenous ERA” is usedherein to mean a material, object or system which is not a part of afruit and which remains after exogenous ERA has been generated from asource of exogenous ERA. The residue may be for example (i) a solidmaterial which served as a support for exogenous ERA itself or for oneor more precursors of exogenous ERA, or (ii) a liquid residue remainingafter a solution of a precursor for an ERA, e.g. 2-chloroethylphosphonic acid, has been used to generate exogenous ethylene and/or asolid residue resulting from the evaporation of solvent from such asolution. The term “residue of exogenous ERA” is used herein to denote achemical compound which results from the reaction of exogenous ERA withthe fruit being ripened (in which case it is optionally part of the ripefruit) or with another substance within the sealed package. The term“ripening” is used herein to mean increasing ripeness; it includes, butis not limited to and generally does not mean, ripening to a point whichresults in a product which in a retail store would be sold as “ripe”.When applied to fruits which ripen through a climacteric, the term“ripening” means ripening the fruits at least through the climacteric.The term “unripe fruits” is used herein to mean fruits which requireripening before they can be sold in retail stores. When applied tofruits which ripen through a climacteric, the term “unripe fruits” meansfruits which have not reached their climacteric. The term “banana” isused herein to include plantains.

Where reference is made herein to sealed packages and sealed containers,and to sealing bags and other containers containing biologicalmaterials, it is to be understood that the sealing can be, but generallyis not, hermetic sealing. Conventional methods for sealing bags andother containers can conveniently be used in this invention. Suchconventional methods include, for example, the use of a cable tie toseal the neck of a polymeric bag. A seal made by conventional methods isnot a hermetic seal, and has the advantage that it permits equilibrationof the pressures inside and outside the bag. If the bag is sealedhermetically, it will generally be desirable to include one or morepinholes in the bag, to achieve such equilibration. The less completethe sealing of the container, the less the influence of the permeabilityof the container on the packaging atmosphere within it. Thus, even apoor seal may be sufficient, or even desirable, for example when thedesired O₂ content of the packaging atmosphere lies between the O₂content of the atmosphere surrounding the package and the O₂ content ofthe packaging atmosphere that would result if the seal was a hermeticseal. Under such circumstances, the sealing could be designed to permita controlled amount of direct exchange between the packaging atmosphereand the atmosphere surrounding the container.

Control Members

The containers used in the present invention preferably, but notnecessarily, include at least one atmosphere control member whichprovides a pathway for O₂ and CO₂, and which preferably comprises agas-permeable membrane comprising (1) a microporous polymeric film, and(2) a polymeric coating on the microporous film. The atmosphere controlmember is preferably a control member as described in one or more ofcopending, commonly assigned U.S. patent application Ser. Nos.08/759,602 and 09/121,082 and U.S. Pat. No. 6,013,293 incorporated byreference herein. The atmosphere control member or members generallyprovide at least 50%, preferably at least 75%, of the O₂ permeability ofthe sealed container.

The microporous polymeric film preferably comprises a network ofinterconnected pores having an average pore size of less than 0.24micron, with at least 70% of the pores having a pore size of less than0.24 micron. Preferably the pores in the microporous film constitute 35to 80% by volume of the microporous film. Preferred microporous filmscomprise a polymeric matrix comprising (i) an essentially linearultrahigh molecular weight polyethylene having an intrinsic viscosity ofat least 18 deciliters/g, or (ii) an essentially linear ultrahighmolecular weight polypropylene having an intrinsic viscosity of at least6 deciliters/g, or (iii) a mixture of (i) and (ii). The microporous filmmay contain 30 to 90% by weight, based on the weight of the film, of afinely divided particulate substantially insoluble filler which isdistributed throughout the film. A preferred process for preparingsuitable microporous films comprises

(A) preparing a uniform mixture comprising the polymeric matrix materialin the form of a powder, the filler, and a processing oil;

(B) extruding the mixture as a continuous sheet;

(C) forwarding the continuous sheet, without drawing, to a pair ofheated calender rolls;

(D) passing the continuous sheet through the calender rolls to form asheet of lesser thickness;

(E) passing the sheet from step (D) to a first extraction zone in whichthe processing oil is substantially removed by extraction with anorganic extraction liquid which is a good solvent for the processingoil, a poor solvent for the polymeric matrix material, and more volatilethan the processing oil;

(F) passing the sheet from step (E) to a second extraction zone in whichthe organic extraction liquid is substantially removed by steam or wateror both; and

(G) passing the sheet from step (F) through a forced air dryer to removeresidual water and organic extraction liquid.

The polymeric coating on the control member preferably comprises acrystalline polymer having a peak melting temperature T_(p) of −5 to 40°C., e.g. 0 to 15° C. or 10 to 20° C., an onset of melting temperatureT_(o) such that (T_(p)−T_(o)) is less than 10° C., and a heat of fusionof at least 5 J/g. The polymer preferably comprises a side chaincrystalline polymer moiety comprising, and optionally consisting of,units derived from (i) at least one n-alkyl acrylate or methacrylate (orequivalent monomer, for example an amide) in which the n-alkyl groupcontains at least 12 carbon atoms, for example in amount 35-100%,preferably 50-100%, often 80-100%, and optionally (ii) one or morecomonomers selected from acrylic acid, methacrylic acid, and esters ofacrylic or methacrylic acid in which the esterifying group contains lessthan 10 carbon atoms. The preferred number of carbon atoms in the alkylgroup of the units derived from (i) depends upon the desired meltingpoint of the polymer. For the packaging of biological materials, it isoften preferred to use a polymer having a relatively low melting point,for example a polymer in which the alkyl groups in the units derivedfrom (i) contain 12 and/or 14 carbon atoms. The polymer can be a blockcopolymer in which one of blocks is a crystalline polymer as defined andthe other block(s) is crystalline or amorphous. Preferred blockcopolymers comprise (i) polysiloxane polymeric blocks, and (ii)crystalline polymeric blocks having a T_(p) of −5 to 40° C. Such apolymer can be prepared by copolymerizing a mixture of reactants whichcomprises (i) at least one n-alkyl acrylate or methacrylate in which then-alkyl group contains at least 12 carbon atoms and (ii) a polysiloxanehaving a copolymerizable group at one end thereof.

Other polymers which can be used to the coat the microporous filminclude cis-polybutadiene, poly(4-methylpentene), polydimethyl siloxane,and ethylene-propylene rubber.

The gas-permeable membrane preferably has one or more of the followingproperties

(i) a P₁₀ ratio, over at least one 10° C. range between −5 and 15° C. orbetween 10 and 20° C. of at least 2.0 to 2.8;

(ii) an OTR at all temperatures between 20° and 25° C. of 2,480,000 to7,000,000 ml/m².atm.24 hr. (160,000 to 450,000 cc/100 in².atm.24hr); and

(iii) an R ratio of at least 1.3, preferably 2.0, particularly at least3.0, especially at least 3.5.

In one embodiment, the control member comprises

(a) the gas-permeable membrane; and

(b) an apertured cover member which lies between the gas-permeablemembrane and the air surrounding the package;

the gas permeable membrane having, in the absence of the apertured covermember,

-   -   (i) an O₂ permeability, OTR_(perm), of at least 155,000        ml/m²·atm·24 hr (10,000 cc/100 in²·atm·24 hr), and    -   (ii) a permeability ratio, R_(perm), of at least 2, and

the apertured cover member being composed of

-   -   (i) a barrier portion having an O₂ permeability, OTR_(bar),        which is less than 0.5 times, preferably less than 0.01 times,        OTR_(perm), and    -   (ii) an aperture portion which comprises at least one aperture        having an area of at least 0.015 in² and through which the        gas-permeable membrane is exposed to the air surrounding the        package, the aperture portion being such that the control member        has a permeability ratio, R_(control), which is at most 0.9,        preferably at most 0.8, times R_(perm), and which is preferably        greater than 1.00.        The aperture portion of the cover member may have an area        A_(open) which is at most 0.04 times A_(perm), where A_(perm) is        the area of the gas-permeable membrane. The aperture portion can        consist of one or more apertures, each aperture having an area,        A_(aperture), less than 0.155 in². For further details of such        atmosphere for control members, reference should be made to U.S.        Pat. No. 6,013,293.

The O₂ permeability of the container at 13° C. per kilogram of fruitstherein (OP13/kg) is preferably at least 700, particularly have least1000, especially at least 1500, ml/.atm.24hrs. The R ratio of thecontainer at 13° C. is preferably at least 2, particularly at least 3.The ethylene permeability of the container at 13° C. per kilogram offruits therein (EtP13/kg) is preferably at least 3 times, particularlyat least 4 times, the OP13/kg of the container.

The permeability of the container, whether or not it includes anatmosphere control member, can be influenced by perforating thecontainer in order to make a plurality of pinholes therein.

Fruits

This invention is particularly useful for (but is not limited to) theripening and/or storage of the wide range of fruits which ripen (orundergo other changes, for example, in the case of citrus fruits,de-greening) when exposed to ethylene, for example apples, apricots,avocados, bananas, blueberries, cherimoyas, dates, figs, kiwis, mangos,melons, peaches, papayas, pears, peppers, persimmons, and plums (all ofwhich go through a climacteric when they ripen), as well as cherries,grapes, lemons, oranges, tomatoes and strawberries. Some aspects of theinvention are especially useful for fruits which in commercial practiceare ripened in ethylene-containing ripening rooms, for example avocados,bananas, Bartlett pears, kiwis, mangos, melons, peppers and tomatoes.

Storage of Unripe Fruits

When the invention is being used to store unripe fruits, it is possibleto produce desired packaging atmospheres by the selection of containerswhich, when sealed around the quantities of fruits in question at theselected storage temperature, have appropriate permeabilities to O₂ andCO₂, and by the selection of an appropriate controlled atmosphere aroundthe sealed packages. Those skilled in the art will have no difficulty,having regard to their own knowledge and the contents of thisspecification, in making appropriate selections to produce a desiredpackaging atmosphere or to make a desired compromise between (i) thecost and inconvenience of obtaining an entirely satisfactory combinationof container and controlled atmosphere, and (ii) the disadvantage ofstoring the fruits in a packaging atmosphere which is in some waysunsatisfactory.

The table below sets out, for some of the fruits for which thisinvention is useful, ranges for the concentrations of O₂ and CO₂ whichmay be used during storage. The invention is, however, useful, forstoring these and other fruits outside the ranges stated in the tablebelow.

Fruit O₂ content CO₂ content Banana 2-5% 3-7% Tomato 3-5% 2-3% Kiwi,nectarine, peach 1-2% 3-5% Fig, blackberry, blueberry, raspberry,  5-10%15-20% strawberry Mango, papaya, pineapple 3-5% 5-8% Avocado 2-5%  3-10%Ripening Unripe Fruits by Exposure to Exogenous ERA

In many aspects of the invention, unripe fruits are ripened by exposureto exogenous ERA while the fruits are in a sealed container. In someembodiments, the exogenous ERA enters the packaging atmosphere throughthe container from the atmosphere surrounding the sealed packages, forexample as a result of

(i) placing the sealed packages in a conventional ripening roomcontaining exogenous ethylene; or

(ii) generating an exogenous ERA-containing atmosphere around the sealedpackages while they are in a closed container, e.g. a shipping ortrucking container, for example by injecting ethylene gas into thecontainer, or by the activation of a source of exogenous ERA which iswithin the container, but not within the sealed packages; such a sourceof exogenous ERA could be packed into the container with the sealedpackages containing the fruits, for example in the form of packageswhich release the ripening agent after a desired delay.

In other embodiments, the ERA is generated within each package byactivating sources of exogenous ERA placed individually in the sealedpackages of unripe fruits. It is also possible to use a combination ofthese embodiments.

The amount of ERA in the packaging atmosphere should be sufficient toassist ripening. Thus the packaging atmosphere in each of the sealedpackages should contain at least 2.5 ppm, typically but not necessarily100 to 3000 ppm, preferably 250 to 1000 ppm, of ERA. When the exogenousERA is added to or generated in the atmosphere surrounding the sealedpackages, the concentration of ERA in the packaging atmosphere willincrease gradually as the exogenous ERA passes through the sealedcontainer, at a rate which depends upon the concentration of ERA in thesurrounding atmosphere. If, therefore, a rapid initiation of ripening isdesired, the concentration of ERA in the atmosphere surrounding thesealed packages is preferably least 500 ppm, particularly at least 1000ppm. The table below shows the time taken to reach an ethyleneconcentration of 100 ppm in the packaging atmosphere of a sealed packageof bananas according to the invention, when placed in a ripening roomcontaining the indicated concentrations of ethylene.

Ethylene concentration ppm 100 200 300 400 500 700 1000 1500 2000 Time5.4 1.5 0.9 0.7 0.5 0.4 0.25 0.2 0.1 (hrs.)

An advantage of ripening fruits in a sealed container in accordance withthe invention, by comparison with conventional ripening by means of acontrolled atmosphere directly in contact with the fruits is that theripe fruits can be substantially less dehydrated. It is believed thatthis is because ripening takes place in a more controlled fashion,resulting in lower peak temperatures in the fruits, which in turnresults in the reduced dehydration. Thus, bananas typically lose 3 to 5%of their weight between packaging directly after harvest and being puton retail sale. I have found that, through use of the present invention,this weight loss can be substantially reduced, for example to less than0.5%. Another benefit, when the ripening is carried out below roomtemperature, is reduced demand on the refrigeration equipment.

The temperature at which ripening is carried out and the concentrationof ERA in the packaging atmosphere influence the rate at which ripeningtakes place. In general, slower ripening results in ripened fruits whichremain in a desired range of ripeness for a longer period. On the otherhand, rapid ripening may be desired, for example in view of deliverydates required by retail outlets. Thus, the atmosphere around the sealedpackages may be above, at, or below ambient temperature. However, it isgenerally preferred that the atmosphere should be at a temperature lessthan 22° C., preferably less than 21° C., for example 16-21° C., or evenlower, for example at a temperature less 18° C. or less than 16° C.,e.g. at 14-15° C.

The atmosphere within the bags will change substantially during theripening process, as the ripening fruits consume O₂ and generate CO₂.The packaging atmosphere, for at least part of the period beforeripening fruits reach their climacteric, may contain at least 10%,preferably at least 12%, particularly 14 to 19%, of O₂, and less than10%, preferably less than 4%, of CO₂, with the total quantity of O₂ andCO₂ being less than 20%, preferably less than 17%. For at least part ofthe period after ripening fruits have passed their climacteric, thepackaging atmosphere may contain at least 0.8%, for example 1.5 to 6% or1.5 to 3%, of O₂, and less than 15%, preferably less than 7%, of CO₂,with the total quantity of O₂ and CO₂ being less than 16%, preferablyless than 10%.

When it is desired to ripen fruits while they are being transported, forexample on a ship or a truck, ripening by means of a source of exogenousERA placed within the sealed packages and/or by means of a source ofexogenous ERA placed within a large closed container containing thesealed packages, is particularly useful. The ripening can be preceded bya storage period in which there is little or no ripening. The ripeningand optional storage process can be controlled so that the fruits are ata desired state of ripeness when they reach their destination. Duringthe process, there may be no need to alter the atmosphere around thesealed packages. However, when the fruits are stored before they areripened, it may be desirable to restrict the amount of oxygen whichenters the sealed packages during storage, in order to prevent or delayripening. When the packages can be surrounded by a controlled atmosphere(for example while being transported in the hold of a suitably equippedship), this result can be achieved by placing the sealed packages in acontrolled atmosphere containing less than the amount of oxygen presentin air (about 21%), for example less than about 12%. The source ofexogenous ERA can make ERA available immediately after packaging thebananas, or after a desired delay. Delayed release of ERA can result,for example, from the use of an exogenous ERA source which (i) isactivated by an increase in moisture content (for example by water whichreaches the ERA source as a result of capillary wicking of water throughan intermediate body which separates a water reservoir from the ERAsource), or (ii) is associated with (e.g. surrounded by or adsorbedonto) a material which releases ERA or one or more precursors for anERA, after a set time or in response to some outside intervention, forexample an increase in temperature.

Any convenient source of exogenous ERA can be used. I have obtained goodresults using 2-chloroethyl phosphonic acid, which is often referred toherein as 2CPA. 2CPA can be used in the form of an aqueous solution, forexample of concentration 3-4%. The rate at which 2CPA generates ethyleneincreases with increasing pH of the aqueous solution, which can beadjusted, for example to more than 4, particularly more than 7, by theaddition of suitable materials, for example buffer solutions and/orsodium bicarbonate solutions. In one embodiment, a 2CPA solution and apH adjuster are adsorbed on the same or different absorbent pads, e.g.paper pads, and the pad(s) placed in the bottom of the bag and coveredwith a polymeric sheet before the unripe fruits are placed in thecontainers. In another embodiment, a solution of 2CPA is applied to theunripe fruits, for example by dipping or spraying, before they areplaced in the bag. The invention also includes the possibility that ripefruits are the source of exogenous ERA, the ripe fruits generatingethylene and being of the same family as, or a different family from,the unripe fruits which are to be ripened. For example, for ripeninggreen bananas, the source of exogenous ERA could be a perforatedcontainer containing apples or bananas which have passed theirclimacteric.

As in the aspects of the invention which involve ripening in anexogenous ERA-containing atmosphere surrounding the sealed packages, theatmosphere within sealed bags containing a source of exogenous ERA willchange during the ripening process. The packaging atmospheres, for atleast part of the periods before and after the climacteric, arepreferably as stated above when the sealed bags are surrounded by anexogenous ERA-containing atmosphere.

Quantities of Fruits

The invention can in principle be used for any quantity of fruits. Insome embodiments, for example when the invention is used for storingand/or ripening green bananas, the sealed container preferably containsat least 4 kg, particularly at least 15 kg, especially 16 to 22 kg ofbananas or other fruits. In other embodiments, smaller quantities areused, for example to increase the shelf life of bananas at a desiredcolor stage.

EXAMPLES

The invention is illustrated in the following Examples, a number ofwhich are comparative Examples, designated by the letter C before thenumber of the example. The bananas, bags and control members used in theExamples were as follows.

Bananas

The bananas were Cavendish bananas, from Ecuador in Examples 1A-B,C11-12, 2, C2, 4A-B and C41-42, from Costa Rica in Examples 5A-C and C5,and from Colombia in the other Examples.

Bags

The large bags were about 0.96 m (38 in.) wide and about 1.2 m (50 in.)long, and were made from polyethylene film about 0.056 mm (2.2 mil)thick (available from Roplast Industries under the tradename RA 3030).The polyethylene film had an OTR at 13° C. of about 2915 (188) and at22° C. of about 4,650 (300), and EtTR at 13° C. of about 11,400 (735)and at 22° C. of about 18,100 (1,170), an R ratio of about 4.5, and aP10 ratio (between 0 and 10° C.) of about 1.76. The small bags wereabout 0.3 m (12 in.) wide and about 0.46 m (18 in.) long, and were madefrom the same polyethylene film.

Control Members

The Type S control members were as described in copending commonlyassigned U.S. application Ser. No. 09/121,082 and correspondingInternational Publication No. WO 00/04787 and comprised a microporouspolyethylene film coated with a polysiloxane/SCC block copolymer. TheType S members had an OTR at 13° C. of about 3,803,850 (245,410) and at22° C. of about 5,000,000 (324,000), an EtTR at 13° C. of about16,280,000 (1,050,300) and at 22° C. of about 19,500,000 (1,260,000), anR ratio of about 3.8, and a P10 ratio (between 0 and 10° C.) of about1.8. The microporous polyethylene film contained 50-60% silica, had athickness of about 0.18 mm (0.007 inch), a tear strength of about 90g, aporosity of about 65%, an average pore size of about 0.1 micron and alargest pore size of 4-10 microns (available from PPG industries underthe tradename Teslin SP 7). The block copolymer was prepared by thereaction of a polydimethyl siloxane terminated one end only by amethacryloxypropyl group (available from Gelest under the tradename MCRM17), 40 parts, dodecyl acrylate, 26.8 parts and tetradecyl acrylate,33.2 parts, as described in Example A7 of U.S. application Ser. No.09/121,082 and corresponding International Publication No. WO 00/04787.

The Type A control members were as described in copending commonlyassigned U.S. application Ser. No. 08/759,602 and correspondingInternational Publication No. WO 96/38495, and comprised the samemicroporous polyethylene film coated with an SCC polymer of dodecylacrylate, 42 parts, tetradecyl acrylate, 53 parts, and acrylic acid, 5parts. The Type A members had an OTR at 22° C. of about 1,705,000(110,000), an R ratio of about 4, and a P10 ratio (between 0 and 10° C.)of about 1.4.

In each Example, the control member was secured to a portion of the bagin which one or more round holes had been cut. The effective area of thecontrol member is about equal to the area of the hole or holes in theportion of the bag to which the control member is attached. However, inExamples 1A-B, C11-12, 2, C2, 3A-D and C31-33, the periphery of thecontrol member was heat sealed to the interior of the bag, thus creatinga control member of the kind described in U.S. Pat. No. 6,013,293. Inthe other Examples, the control member was secured to the exterior ofthe bag by means of a layer of a pressure sensitive adhesive on theperipheral margin of the control member.

The color stages referred to in the Examples are those accepted by theindustry and as shown below.

Color stage Description 1 95% green 2 80% green, 20% slightly yellow 350% yellow, 50% green 4 80% yellow, 20% light green 5 95% yellow, withslight green color at stem and blossom end 6 100% yellow 7 100% yellowwith brown sugar spots

Bananas are preferably at color stage 3.5 to 5 when put on retail sale.

Many of the Examples are summarized in Tables 1-8 below. In the Tables,when more than one result is given for a particular Example, thisreflects the fact that more than one test was carried out under the sameconditions.

Examples 1A-B, C11-12, 2 and C2

Each of these Examples uses a large bag. In Examples C11, 1A-B and 2,each bag has one S-type control member placed under two or more holes inthe bag. In Example C11, the control member had an area of 1935 mm² (3in²) and was placed under two holes, each of diameter 20.6 mm (0.81in.). In Example 1A, the control member had an area of 6450 mm² (10 in²)and was placed under 6 holes, each of diameter 20.6 mm (0.81 in.). InExamples 1B and 2, the control member had an area of 12,900 mm² (20 in²)and was placed under 6 holes, each of diameter 28.7 mm (1.13 in). Eachbag was packed with about 20 kg (44 lb) of green bananas. The bananashad been harvested at week 11 and maintained at 13-14° C. for about 11days after harvest before being packed. Except in Examples C12 and C2,excess air was extracted from the bags using a vacuum pump, and the bagswere then sealed using tie wraps. In Examples C12 and C2, the bags wereleft open. The bags were maintained at 13° C. for an extended time,Examples 1A, 1B, C11 and C12 being terminated at day 62, and Examples 2and C2 being terminated at day 40. The results are given in Table 1below. In Example 2, traces of ethylene (generated by the ripening ofthe bananas) remained in the test chamber from Example 1 and caused thebananas to ripen more rapidly than in the otherwise substantiallyidentical Example 1B. This demonstrates the desirability of excludingethylene when long storage periods are needed (and conversely, theability to accelerate ripening when desired).

TABLE 1 Example No. C11 1A 1B C12 2 C2 Control member yes yes yes no yesNo Total area of holes in bag under 670 2000 3880 — 3880 — controlmembers (mm²) Color stages first change at day >62 44 44 12 26 15 daysto change from 3.5 to 4.5 — — — — 4.5 * days to change from 3.5 to 5 —** 11 7 # * Weight loss (%) on day 26 — — — — 0.35 3.7 on day 41 0.380.45 0.60 4.73 — — Taste and texture on day 40 — — — — Exct ♦ on day 62UGH Exct Exct Overripe — % O₂ (approximate) at day 7 5.1 11.9 13.8 atm —atm at day 8 — — — atm 14.35 atm at day 47 (after climacteric) 5.0 0.962.2 atm 2.15 atm % CO₂ (approximate) at day 7 5.3 3.6 3.05 atm — atm atday 8 — — — atm 3.05 atm at day 29 (after climacteric) — — — atm 8.0 atmat day 47 (after climacteric 5.3 7.9 8.4 atm — UGH unripe, green andhard. * the bananas had a color of 4.5 when the test was terminated atday 62 Exct excellent taste and texture # test terminated at this point;extrapolation indicates that time to change from color 3.5 to 5 would be5.9 days. ♦ Bananas removed on day 26 because they were over-ripe.

Examples 3 and C31-33

Each of these Examples uses a large bag. In Examples C31-33 and 3, eachbag has one S-type control member placed under one or more holes in thebag. In Example C31, the control member had an area of 967 mm² (1.5 in²)and was placed under a single hole of diameter 20.6 mm (0.81 in.). InExample C32, the control member had an area of 1935 mm² (3 in²) and wasplaced under 2 holes, each of diameter 20.6 mm (0.81 in.). In ExampleC33, the control member had an area of 3225 mm² (5 in²) and was placedunder 4 holes, each of diameter 19 mm (0.75 in.). In Example 3, thecontrol member had an area of 12,900 mm² (20 in²) and was placed under 6holes, each of diameter 25 mm (1 in.). In Example C34, the bag did nothave a control member. Each bag was packed with about 18.1 kg (40 lb) ofgreen bananas. The bananas had been harvested at week 13, and maintainedat 13-14° C. for about 11 days after harvest before being packed. Exceptin Example C34, excess air was extracted from the bags using a vacuumpump, and then securely tied (the bags were not, however, as completelysealed as in Examples 1 and 2). In Example C34, the bags were left open.The sealed bags were cooled to about 13° C. and shipped to Gulfport,Miss., and then to San Francisco, Calif., maintaining the temperature atabout 13° C. In San Francisco, 36 days after packing, half the bags ineach Example were opened, and the other half left intact. All the bagswere then exposed to exogenous ethylene (500-1000 ppm) in a commercialripening room for about 24 hours. The bananas in the opened bags ripenedrapidly in the expected way; thus by day 43, their color was 6, by day46 their color was greater than 7, and by day 49, they were overripe.The bags which were still sealed were opened on day 49. The results forthe bags opened on day 49 are shown in Table 2 below. These Examplesdemonstrate that bananas harvested at 13 weeks can be transported in asuitably designed bag, and can be ripened into an excellent product byexposure to exogenous ethylene, either through the bag or after openingthe bag.

TABLE 2 Example No. C31 C32 C33 3 C 34 Control member yes yes yes yes noTotal area of hole(s) in bag under control 335 670 1140 3040 — member(mm²) Days to change from color stage 3.5 to >8 >8 >8 5.5 DDU colorstage 5 Taste and texture on day 49 SGU SGU SGU Exct DDU % O₂(approximate) at day 23 8.6 9.8 12.7 15.5 at day 46 2.9 0.6 1.8 2.2 %CO₂ (approximate) at day 23 4.45 3.65 3.3 2.85 at day 46 13.8 11.4 5.09.0 SGU soft, green and unpalatable DDU dehydrated, decayed andunpalatable by day 47 (day 11 after exposure to ethylene) Exct excellenttaste and texture

Examples 4A, 4B, C41 and C42

Each of these Examples uses a small bag. In Examples 4A-B, each bag hasone A-type control member placed over four or five holes in the bag. InExample 4A, the control member had an area of 145 mm² (5.7 in²) and wasplaced over four holes each of diameter 19 mm (0.75 in.). In Example 4B,the control member had an area of 4516 mm² (7 in²) and was placed over 5holes, each of diameter 19 mm (0.75 in.). In Example C41, the controlmember and the holes under it were as in Example 4A, except that thecontrol member was an uncoated microporous film. In Example C42, the bagwas intact except for 200 pinholes each about 0.5 mm (26 gauge) indiameter. Each bag was packed with about 1.35 kg (3 lb) of green bananaswhich had been maintained at 13-14° C. for about 11 days after harvest.Except in Example C42, excess air was extracted from the bags using avacuum pump, and the bags were then securely tied. In Example C42, thebags were left open. After three days, to allow the packaging atmosphereto equilibrate, the bags were exposed to exogenous ethylene (500-1000ppm) in a ripening room. The results are shown in Table 3 below. TheseExamples demonstrate that small quantities of bananas can be ripened ina suitably designed bag, and can remain in the bag in excellentcondition for several days longer than bananas exposed to the air.

TABLE 3 Example No. 4A 4B C41 C42 Control member yes yes

no Total area of holes in bag over 1140 1425 1140 — control member (mm²)Color stage on day 10 after 4.0 4.4 7.0 6.8  ethylene treatment Weightloss (%) on day 10 after 0.57 0.72 1.05 0.61 ethylene treatment Taste &texture on day 10 after Exct Exct Over- Over- ethylene treatment riperipe

 uncoated microporous film Exct excellent taste and texture

Examples 5A, 5B, 5C and C5

These Examples show that the bananas generate heat more evenly whenripened in a container including an atmosphere control member. In eachExample, a large bag was packed with about 18.1 kg (40 lb.) of greenbananas. The green bananas had been harvested 13 days previously and hadbeen stored at 13-14° C. since harvest. A temperature sensor (availablefrom Sensitech, Beverly, Mass., under the tradename Temptale P) wasinserted into one banana in each bag. In each of Examples 5A, 5B and 5C,the bag had two S-type control members, each having an area of 11,300mm² (17.5 in²). Each control member was placed over a single hole in thebag, the hole having an diameter of 70 mm (2.75 in.) in Example 5A, 74.4mm (2.93 in.) in Example 5B, and 78.7 mm (3.1 in.) in Example 5C. InExample C5, the bag was perforated so that the bananas were surroundedby air. The bags were then sealed with rubber bands. The sealed bagswere placed in a refrigerated room at about 13° C. After about 84 hours,the temperature of the room was raised to about 16.7° C. and after about12 hours, an ethylene generator was used to provide an initial ethyleneconcentration in the room of 500-1000 ppm. About 24 hours after thegeneration of ethylene had begun, the room was vented. The temperatureof the bananas was monitored for about 15 days, and reached a peak atabout 60 hours after the generation of ethylene had begun. At that time,the concentration of O₂ and CO₂ was measured. The results are shown inTable 4 below. It will be seen that the peak temperature wassubstantially lower in the bags containing control members than in theperforated bag.

TABLE 4 Example No. 5A 5B 5C C5 Control member yes yes Yes no Total areaof holes in bag under 7700 8700 9700 — control members (mm²) Temperature(° C.) of bananas 12 hrs 16.3 15.9 15.7 16.6 after temperature of roomwas set to 16.7° C. Peak Temperature ° C. 21.2 21.1 20.9 23.9 Differencebetween peak temperature 4.9 5.3 5.2 7.3 and 16.6° C. % O₂ 60 hoursafter injection of 2.2 1.75 1.9 20.95 ethylene % CO₂ 60 hours afterinjection of 7.95 6.1 7.4 0.03 ethylene

Examples 6A-E

Each of these Examples uses a large bag having two S-type controlmembers, each control member having an area of 11,300 mm² (17.5 in²).Each control member was placed over seven holes in the bag, each hole ofdiameter 25.4 mm (1 in). A paper pad about 300×400 mm (12×16 in.)impregnated with an aqueous solution of 2CPA (3.9%) was placed in thebottom of each bag and covered with a sheet of polyethylene. The amountof the solution varied from Example to Example, and is shown in Table 5below. About 18.1 kg (40 lb.) of green bananas were then placed in eachbag, and the bags were sealed with rubber bands. The green bananas hadbeen maintained at 13-14° C. for about 11 days after harvest. The sealedbags were left in a cold room at 13-14° C. The color stage of thebananas was monitored, and Table 5 below shows the time in days taken toreach color stages 4 and 5.5.

TABLE 5 Example No. 6 A 6B 6C 6D 6E Control member yes yes yes yes yesTotal area of holes in bag 7100 7100 7100 7100 7100 under controlmembers (mm²) mL of 3.9% 2CPA solution 30 50 100 200 500 on paper padDays to color stage 4 11 10.8 10.6 11 9.6 * 20.4 20.1 12 12 * 10.5 11 1111 Days to color stage 5.5 17.5 * 17.4 16 16.1 * * 24.2 16 16.9 * 17.517.4 16 16.3 Days from color stage 4 to 6.5 — 6.8 5 6.5 color stage 5.5— — 3.1 4 4.9 — 7 6.4 5 5.3 * this color stage had not been reached whenthe experiment was terminated after 27 days.

Examples 7A-D and C71-74

The procedure of Example 6 was followed except for the changes notedbelow.

1. In Examples 7A-D, there was a single hole, diameter 82.5 mm (3.25in.), under each of the two control members. The total area of the holeswas 10,700 mm².

2. In Examples 7A, 7B and 7C and in comparative Examples C72 and C73, apaper pad impregnated with 0.1 N NaHCO₃ solution was placed adjacent tothe paper pad impregnated with 2CPA solution, thus increasing the pH ofthe 2CPA solution and increasing the rate at which ethylene wasgenerated. The amount of the NaHCO₃ solution varied from Example toExample as shown in Table 6 below.

3. In Examples 7D and C74, 2CPA was not used, but three days afterpacking, the bags were exposed to ethylene for 24 hours in aconventional ripening room at 16.7° C. and containing 500-1000 ppm ofethylene.

4. Comparative Examples C71-74 were carried out in which no ethylene wasused (C71), or the bag was sealed but did not have a control member(C72-73), or the bag was not sealed (C74).

5. The ethylene concentration in the bags was measured at various timesafter packing.

The results obtained are shown in Table 6 below.

TABLE 6 Example No. 7A 7B 7C 7D C71 C72 C73 C74 Control yes yes yes yesyes no no no member mL 3.9% 30 30 30 no no 30 30 no 2CPA solution mL 0.1N 15 30 60 no no 13 30 no NaHCO₃ Exposed to no no no yes no no no yesethylene in ripening room Days to color 12 10.2 6.2 6.5 4.2 stage 4 12.510.2 9.4 6.5 4.5 15 8.4 9.8 7.1 4.5 Days to color * * 9.5 11.5 6.6 stage5.5 * * 12.5 12 7 * * 12.9 12.3 7.2 Days from — — 3.3 5 2.4 color stage4 to — — 3.1 5.5 2.5 color stage 5.5 — — 3.1 5.2 2.7 Color after 15 2 22 days ppm ethylene after  0 hrs 0.47 4.11 8.65 5.72 10.7  7 hrs 0.582.36 10.0 7.81 13.3 72 hrs 0.68 1.94 4 10.8 5 79 hrs — 3.28 6.66 5 20.54.7 9.43 1 16.6 5 % O₂ after 3.73 3.97 3.72 0.21 0.34 15 days % CO₂after 6.23 6.2 4.67 27.3 25.5 15 days * this color stage had not beenreached when the experiment was terminated.

Examples 8A-J and C81-83

Examples 8A-J and C81-83 followed the same procedure as Examples 7A-Cand C71-74 except for the changes noted below.

1. The ethylene, O₂ and CO₂ concentrations were determined at differenttimes.

2. In some of the examples, the second paper pad was impregnated with 30mL of an aqueous buffer solution (i) containing potassium phthalate andhaving a pH of 4, (ii) containing dibasic sodium phosphate, monobasicpotassium phosphate, sodium chromate and potassium dichromate, andhaving a pH of 7, or (iii) containing sodium carbonate and sodiumbicarbonate and having a pH of 10. These buffer solutions are availablefrom Orion Research Inc., Beverley, Mass. USA

3. In Examples 8H and C83, the bag was taken to the ripening room 3 daysafter packing.

4. In Example 8G, the sealed bags were left in a room at about 21° C.(in the other Examples, the room was at 13-14° C.).

5. In Example C83, the bag was not sealed.

The results are shown in Table 7 below.

TABLE 7 8A 8B 8C 8D 8E 8F 8G 8H C81 C82 C83 Control member yes yes yesyes yes yes yes yes yes No no mL 3.9% 2CPA 30 30 30 30 30 30 30 no no 30no solution mL 0.1 N NaHCO₃ no no no 45 60 75 60 no no 60 no 30 mL ofbuffer pH 4 pH 7 pH no no no no no no No no having 10 Exposed toethylene no no no no no no no yes no No yes in ripening room Days tocolor stage 4 11.9 15.4 13.1 9.4 8.5 9.0 8.2 7.7 * * 3.7 13.0 11.3 11.59.0 9.3 8.1 7.6 — — — 3.9 14.3 10.1 10.8 10.1 8.0 8.1 6.7 10.6 — — 3.9Days to color stage — — — 15.7 13.8 12.4 14.8 14 * * 5 5.5 — 15.3 — 12.313.1 11.4 12.2 — — * 6 — — 16.6 15 11.9 11.4 9.0 * — — 6 Days from colorstage * * — 6.3 5.3 3.4 6.2 6.3 — — 1.3 4 to color stage 5.5 * 4 — 3.33.8 3.3 4.6 — — — 2.1 * * 5.8 4.9 3.9 3.3 2.3 — — — 2.1 ppm ethyleneafter 24 hrs 0.88 1.67 1.37 3.25 4.39 5.58 10.9 0.49 0.39 39.5 0 % O₂after 8 days 3.72 5.58 2.93 3.2 2.39 2.52 1.95 2.97 17 0.3 — % CO₂ after8 days 4.73 4.7 5.3 4.97 5.13 5.47 7.97 4.73 1 17.6 — * this color stagehad not been reached when the experiment was terminated after 17 days.

Examples 9A-C and C91-92

The procedure of Example 6 was followed, except for the changes notedbelow.

1. There was a single hole, diameter 82.5 mm (3.25 in.), under eachcontrol member. The total area of the hole was 5350 mm².

2. No 2CPA-impregnated paper pad was placed in the bag.

3. The bananas, before being packed into the bag, were dipped into adilute aqueous solution of 2CPA. The concentration of the 2CPA variedfrom Example to Example as shown in Table 8 below.

4. Comparative Examples C91 and C92 were carried out in which the bagdid not have a control member (C91) or the bananas were not treated with2CPA solution (C92). Comparative Example C91 is the same as thecomparative Example C71.

The results obtained are shown in Table 8 below.

TABLE 8 Example No. 9A 9B C91 C92 Control Member yes yes no YesConcentration of 2CPA (ppm) 1116 128 1116 0 Days to color stage 4 11.914.6 * * 10 * * * 11.9 11 * * Days to color stage5.5 * * * * * * * * * * * * * this color stage had not been reached whenthe experiment was terminated after 27 days.

Table 9 below shows, for each of the bags in Examples 5A-C, 6A-E and7A-E, the permeability of the bag to O₂ and to ethylene (“Et” in Table9), and the respective contributions of the control member and theremainder of the bag. For this calculation, the size of the bag, aftersealing, was assumed to be 0.96×1.04 m (38 in.×41 in.), i.e. to have atotal area of 2 m² (3115 in²).

TABLE 9 Perm. of bag Perm. of bag Perm. of rest Example (mL/atm · 24 hr)at at 13° C./kg of Hole area Perm. Of of bag at No. 13° C. bananas (m²)ACM at 13° C. 13° C. C11 O₂ 8,450 O₂ 470 0.000670 O₂ 2,550 O₂ 5,900 Et36,000 Et 2,000 Et 10,900 Et 25,100 1A O₂ 13,500 O₂ 745 0.002000 O₂7,600 O₂ 5,900 Et 57,650 Et 3,185 Et 32,550 Et 25,100 1B O₂ 20,650 O₂1,140 0.003880 O₂ 14,750 O₂ 5,900 Et 88,250 Et 4,875 Et 63,130 Et 25,1002 O₂ 20,650 O₂ 1,140 0.003880 O₂ 14,750 O₂ 5,900 Et 88,250 Et 4,875 Et63,130 Et 25,100 C31 O₂ 7,200 O₂ 395 0.000335 O₂ 1,300 O₂ 5,900 Et30,650 Et 1,695 Et 5,500 Et 25,100 C32 O₂ 8,500 O₂ 470 0.000670 O₂ 2,550O₂ 5,900 Et 36,000 Et 2,000 Et 10,900 Et 25,100 C33 O₂ 10,250 O₂ 5650.001140 O₂ 4,350 O₂ 5,900 Et 43,650 Et 2,400 Et 18,550 Et 25,100 3 O₂17,450 O₂ 965 0.003040 O₂ 11,550 O₂ 5,900 Et 74,600 Et 4,120 Et 49,500Et 25,100 5 A O₂ 35,000 O₂ 1,935 0.007700 O₂ 29,100 O₂ 5,900 Et 149,800Et 8,280 Et 124,700 Et 25,100 5B O₂ 39,000 O₂ 2,155 0.008700 O₂ 33,100O₂ 5,900 Et 166,650 Et 9,200 Et 141,550 Et 25,100 5C O₂ 42,900 O₂ 2,3700.009700 O₂ 37,000 O₂ 5,900 Et 183,550 Et 10,150 Et 158,450 Et 25,100 6A-E O₂ 32,840 O₂ 1,815 0.007100 O₂ 26,940 O₂ 5,900 Et 140,500 Et 7,750Et 115,400 Et 25,100 7 A-E O₂ 46,500 O₂ 2,570 0.010700 O₂ 40,600 O₂5,900 Et 199,200 Et 11,000 Et 174,100 Et 25,100

Example 10

Three trials were carried out to compare bananas transported and ripened(a) conventionally in 12 conventional bags as controls, and (b) inaccordance with the invention in 36 bags having atmosphere controlmembers. Each bag was supported by a cardboard box. The conventionalbags were about 1 m. (38.5 in.) by 1.25 m. (49.5 in.) and were made ofpolyethylene film about 0.18 mm (0.0007 in.) thick. Each conventionalbag was perforated with about 312 holes, each about 12.5 mm (0.5 inch)in diameter. The bags used in accordance with the invention were about 1m. (39.75 in.) by 1.2 m (46.25 in.) and were made of a film of a blendof polyethylene and ethylene/vinyl acetate copolymer about 0.05 mm(0.002 in.) thick. Each bag had two S-type atmosphere control members,each control member being about 145 mm (5.625 in.) by 120 mm (4.72 in.)and being secured to the bag by a layer of adhesive about 11 mm (0.44in.) wide around its periphery. Under each atmosphere control member,the bag had seven holes each about 25 mm (1 in.) in diameter.

In Columbia, each bag was packed with about 20 kg. of green, freshlyharvested bananas. The necks of the bags of the invention were sealedwith rubber bands. The necks of the conventional bags were not closed.The bags were weighed and then transported at about 14.5° C. (58° F.) toWatsonville, Calif., U.S.A., where, 13 days after harvest, they wereplaced in a commercial ripening room containing ethylene for 24 hours atabout 16.5° C. (62° F.). The room was then vented and maintained atabout 16.5° C. (62° F.) for the next 24 hours, at about 15.5° C. (60°F.) for the next 48 hours, and at about 14.5° C. (58° F.) for the next24 hours. The bananas were then maintained at about 21° C. (70° F.). Thetable below shows the average weight loss of the bags, and the color ofthe bananas in the bags, on the day indicated. The sealed bags were notopened until the day indicated in the table below.

Trial 1 Trial 2 Trial 3 Invention Control Invention Control InventionControl Days 11 9 10 9 10 9 after harvest Weight 0.44 5.17 0.4 4.6 0.074.66 loss (%) Color 5.25 7 5.75 9 5.3 7The results reported in this table show clearly that the practice of theinvention results in bananas which lose less weight through dehydrationand which remain at a desired color stage for a longer time

The invention defined by the claims below is narrower in scope than theinvention disclosed in the Summary of Invention, Detailed Descriptionand Examples above. I intend to file one or more continuing applicationsto claim some or all of the aspects and embodiments of the inventionwhich are disclosed in the Summary of Invention, Detailed Descriptionand Examples above, but not literally claimed by the claims in anypatent issued on this application. Therefore, readers of thisspecification should be aware that I am not dedicating to the public anypart of the invention broadly described in this specification, even ifit does not fall within the literal scope of the claims in any patentissued on this application.

1. A sealed package comprising, (a) a sealed polyethylene bag, and (b)within the sealed polyethylene bag, (i) bananas, and (ii) a packagingatmosphere around the bananas which is an equilibrium atmospherecomprising O₂, CO₂, and exogenous ethylene or the residue of exogenousethylene, the O₂ content having a substantially constant value which is1.5 to 6%, the CO₂ content having a substantially constant value whichis less than 15%, and the total quantity of O₂ and CO₂ being less than16%; the sealed polyethylene bag comprising at least one atmosphere,control member which (i) provides a pathway for O₂, CO₂ and ethylene toenter or leave the packaging atmosphere, and (ii) provides at least 50%of the oxygen permeability of the sealed bag; and the sealedpolyethylene bag having an O₂ permeability at 13° C. per kg of bananasin the package (OP13//kg) of at least 1500 ml/atm,24hrs, an ethylenepermeability at 13° C. per kig of bananas in the package (EtP13//kg)which is at least 2 times the OP13//kg, and an R ratio at 13° C. of atleast
 2. 2. A package according to claim 1 wherein the bananas and thepackaging atmosphere are the sole contents of the sealed polyethylenebag.
 3. A package according to claim 1 wherein the sealed polyethylenebag has an EtP13//kg which is at least 3 times the OP13//kg.
 4. Apackage according to claim 1 wherein the bananas have passed the peak oftheir climacteric.
 5. A package according to claim 1 wherein thepackaging atmosphere is at a temperature less than 18° C.
 6. A packageaccording to claim 1 wherein the packaging atmosphere is at atemperature less than 16° C.
 7. A package according to claim 1 whereinthe polyethylene bag contain 16-22 kg of the bananas.
 8. A packageaccording to claim 1 wherein the atmosphere control member (i) comprisesa microporous polymeric film and a polymeric coating on the microporousfilm.